1. Field of the Invention
The present invention relates to the field of communication technologies. More particularly, the present invention relates to a method for processing a Radio Link Failure report and a method for adjusting a mobile parameter.
2. Background of the Invention
System Architecture Evolution (SAE) is an evolved system structure proposed by the 3rd Generation Partnership Project (3GPP). At an initial stage of network deployment or during operation of a whole mobile network, a large amount of human labor is required for configuring and optimizing a network parameter (particularly for setting a radio parameter), so as to ensure a favorable coverage and capacity, mobile robustness, load balance in mobility, access rate of user equipment, etc. Therefore, a Self-Optimization Network (SON) requirement is proposed in the SAE system. A self-optimization architecture according to the related art is as illustrated in FIG. 1.
After being powered up, an evolved base station (evolved Node B, eNB) begins a self-configuration process. As illustrated in FIG. 1, the self-configuration includes: (A) Basic settings and (B) Initial radio parameter configuration. Specifically:
(A) Basic settings include: a-1˜a-4 and the like as illustrated in FIG. 1, in which:
a-1 denotes configuring an IP address for the eNB and detecting an Operation, Administration and Maintenance (OAM);
a-2 denotes authentication between the eNB and the network;
a-3 denotes, for a home base station, finding a corresponding gateway; and
a-4 denotes downloading the operation parameter and software of the eNB.
(B) initial radio parameter configuration includes: b-1˜b-2 and the like as illustrated in FIG. 1, in which:
b-1 denotes configuring a neighbor cell list; and
b-2 denotes configuring a coverage capacity related parameter.
The above self-configuration is performed according to ideal scenarios such as experience, simulation, and the like. Actual network performance may vary depending on influences of buildings, climates, surrounding environments, etc. Therefore, after the self-configuration is completed, the configuration of many parameters is probably not optimal. In order to gain better performance for the network so as to meet the requirements of operators and users, the optimization process of the network is very important. At present, self-optimization having relatively great importance includes: the self-optimization of the neighbor cell list, the self-optimization of the coverage and capacity, the self-optimization of the mobile robustness, the self-optimization of the load balance, the self-optimization of a Random Access Channel (RACH) parameter, power saving, interference reduction, etc. Specifically, the interference reduction may be a part of the self-optimization of the coverage and capacity. In FIG. 1, (C) only illustrates a portion of self-optimization operations by taking “c-1: The self-optimization of the neighbor cell list,” and, “c-2: The self-optimization of the coverage and capacity,” as examples.
In the self-optimization of the mobile robustness, the most important issue is the way to determine if handover is too late or too early. In the self-optimization of the coverage and capacity, another relatively important issue is to determine whether a coverage hole exists.
In existing methods for determining too late handover, determining too early handover, and determining if a coverage hole exists, the following operation is common. When a User Equipment (UE) encounters Radio Link Failure (RLF) in a cell 1 controlled by an eNB1 and selects a cell 2 controlled by an eNB2 to re-establish a Radio Resource Connection (RRC), the UE sends an RRC re-establishment request message to the eNB2. The Physical Cell Identifier (PCI) of the cell 1, the Cell Radio Network Temporary Identifier (CRNTI) of the UE in the cell 1, and the short information of Media Access Control used for data Integrity of signaling messages (short MAC-I) are carried in the RRC re-establishment request message. The eNB2 determines the base station (i.e., the eNB1) that controls the cell corresponding to the PCI according to the PCI, and sends an RLF report to the eNB1. The CRNTI of the UE in the cell 1, the PCI of the cell 1, and the PCI of the cell 2 are carried in the RLF report.
After receiving the RLF report, the eNB1 based thereon determines whether too late handover and/or too early handover have occurred, or determines whether a coverage hole exists.
The operation in common for the above three methods actually relates to a processing manner for the RLF report. The above existing processing manner for the RLF report has a problem in that, after the eNB2 receives the RRC re-establishment request message from the UE, if there are two or more adjacent cells (e.g. controlled by the eNB1 and an eNB3, respectively) having the same PCI, the eNB2 may be incapable of determining the eNB to which the RLF report should be sent. In case of erroneous sending, the eNB may be caused to make a wrong determination, thus leading to an adverse influence on network performance. This problem also occurs in other processes that need to perform the self-optimization based on the RLF report.
The self-optimization of the mobile load balance seeks to ensure the load balance between adjacent cells or between cells having overlapped coverage, or to transfer a part of the load contained in a congested cell to an adjacent cell or a cell having overlapped coverage. This may be implemented by switching the UE or by adjusting the mobile parameter. The mobile parameter includes a cell switching parameter and a cell re-selection parameter. In order to avoid a ping-pong effect resulting from UE switching, a cell needs to negotiate with the adjacent cell when adjusting its mobile parameter. How to ensure a cell adjusts the mobile parameter with all its adjacent cells in a harmonious manner is a problem to be addressed at present.
The occurrence of the above problem causes degradation of the self-optimization effect, and the network performance cannot be ensured effectively.
Therefore, a need exists for a method and system for processing an RLF report and for adjusting a mobile parameter, so as to enhance the self-optimization effect, thus to improve network performance.